1. Field of the Invention
The present invention relates generally to electric power generation, in particular for electric vehicles, and the rechargeable power systems used to power the electric motors present in such vehicles. More particularly, the present invention relates to an acid-base concentration cell for use in powering an external system, such as an electric vehicle, wherein the acid and base electrolytes for the cell are stored in external tanks and cycled to the cell on demand. The present invention also relates to any application in which a high energy density, high power density, rechargeable or refuelable electric power source is required.
2. Description of Related Art
The foremost consideration in the design of electric vehicles is the battery or fuel cell. In order for electric vehicles to be of practical use, it is essential that batteries or fuel cells having sufficient energy density and power density be developed. The energy density of a battery determines the range or distance a vehicle can be driven between recharging. On the other hand, power density determines the power available for acceleration and high speed driving. It is important that the battery or fuel cell used to power the drive train motors in an electric vehicle have both high energy density and power density.
Electric vehicles are now generally powered by lead-acid batteries. Such batteries are heavy and have a relatively limited cycle life when used at the high depth of discharge required for providing the most range for electric vehicles. Even at high depth of discharge, the low energy density of lead-acid batteries provides a range of only about 50 miles for a small van. In addition, recharging of lead-acid batteries is a relatively slow process requiring a battery charger which must be connected to a source of electricity. Other potential power sources have been suggested, such as sodium-sulfur batteries. However, the materials used in such batteries present problems of their own and sodium-sulfur batteries must be operated at high temperatures.
It would be desirable to provide a battery or fuel cell which can be either conventionally recharged, or refueled quickly without relying on conventional battery recharging systems. Also, it would be desirable to refuel using inexpensive, commonplace, non-fossil, non-polluting, non-explosive, non-flammable, chemically stable liquids. Further, it would be desirable to provide a power system wherein both the energy density and power density are high enough to power the drive train motors of an electrical vehicle to achieve performance characteristics, i.e. acceleration, top speed and range, which are acceptable by present day automotive standards.
In addition to electric vehicles, other possible uses for this invention include all applications for which secondary batteries or fuel cells can be used. Some such uses are remote location power, aircraft batteries, military batteries, and utility peak power shaving.